DE4320893C1 - Process for the surface coating of molded wood parts - Google Patents

Description

The invention relates to a method for surface coating layering of molded wood parts.

Such molded wood parts with a wooden surface are used use for example for the interior of motor vehicles det. The surface of such molded wood parts, the designed as solid parts or as molded plywood can be, but also have a veneered surface can, with a clear varnish or another provided transparent surface coating material, so that on the one hand a possibly shiny and hard-wearing capable surface, while on the other hand through this usually referred to as transparent painting by visible surface coating the structure of the wood not only remains visible, but even emphasized becomes.

In conventional manufacturing processes, those are used Surface coating materials on those to be coated Surfaces have been sprayed on or painted on. So that Surfaces are free of inclusions and completely uniform, it is necessary to take increased precautionary measures In some cases, layers of paint have to be applied in several stages  be applied to each other. Such processes are expensive moreover, it can not be avoided that by A conclusions and other malfunctions committee parts are produced.

The object of the invention is a generic method so that the surface coating of the process here is simplified and that at the same time the quality of Surface coating is improved.

This task is described in a method of the beginning benen type solved according to the invention in that the Wooden molded part to be coated in a cavity inserts, the inner wall of the wood molding in the area of has a small distance from the surface to be coated and thereby between the inner wall and the one to be coated Surface over the entire surface to be coated area-extending gap space with a substantially constant Thickness forms that the cavity is at least partially evacuated that one during evacuation or after liquid surface coating material in the cavity filled and that after the gap is completely filled with the liquid material hardens inside the cavity.

In contrast to conventional techniques of surface treatment layering where the material is on the free surface is applied, the molded part is in a cavity as it were embedded in the liquid coating material, the coating material being the gap between layered surface and inner wall of the cavity fully constantly fills, so that the geometry of this gap the Geometry of the applied surface layer corresponds. This is ensured by evacuating the cavity  conditions that no gas bubbles are inserted into the surface layer be bedded, the evacuation also leads to the fact that filled liquid material is completely even in all free areas of the gap pour and the completely filled completely homogeneously. This in turn ge maintains a homogeneous and uninterrupted quality of Surface coating.

This filling can be improved by the fact that the liquid surface coating material under increased Filled pressure into the cavity, so practically in the gap presses in space.

The hardening of the filled, liquid surface material can be done in different ways, they are chemical or physical hardening processes possible, for example by Heat. It is particularly cheap if you have the liquid Surface material after filling the cavity through the radiation-permeable walls of the cavity through with a the hardening of the liquid surface measure terials promoting radiation, especially if the radiation is electromagnetic radiation in the uv range is. Then cavity molds are used which are suitable for this radiation is transparent, for example glass molds.

As a liquid surface coating material you can preferably synthetic resins on polyurethane, polyester or acrylic use base.

This also makes the process particularly economical perform mix that the coated wood part after removed from the cavity after curing and without further  Surface processing leaves. This is particularly possible Lich when the inner wall of the cavity is completely smooth is then you get a high-gloss surface of the upper surface coating.

On the other hand, it is also possible to have a cavity with a structured inner wall is used, so that one Be layering with a corresponding surface structure enough, for example a matt surface or a corrugated surface.

In a first embodiment of the method described can be provided that the wooden molded part in the Arranges cavity on all sides between the surface of the Wood molding and the inner wall of the cavity a gap is trained. You get an all-round and full Constantly uniform coating of the inserted wood mold partly, a complete casing, so to speak.

However, it is also possible in another embodiment Lich, that the area of the molded wood part in areas Telbar creates on the inner wall of the cavity, so that only in the remaining surface areas a gap between the surface to be coated and the inner wall of the cavity is arranged. This also allows a Be in some areas achieve stratification. In many cases it is enough for indoor clothing parts of motor vehicles, for example, if the surface facing the interior accordingly is layered, the back of such molded wood parts can in remain essentially uncoated. Of course intermediate forms are also conceivable, the coating on the the side facing outwards is thicker than the coating  on the opposite side. This can be done by a corresponding Unsymmetrical arrangement of the molded wood part in the Reach cavity.

The described invention extends of course not only on the process, but also on molded parts that are made using this method.

The following description of preferred embodiments the invention serves in connection with the drawing of the nä here explanation. Show it:

Figure 1 is a sectional view through a mold with a cavity and an inserted molded part with a gap surrounding the molded part on all sides.

Fig. 2 is a sectional view taken along line 2-2 in Fig. 1 and

Fig. 3 is a view similar to FIG. 1 with a one-sided surface fitting on the inner wall of the cavity.

In the drawing, a shape 1 is shown, which surrounds a cavity 2 which is closed on all sides. In this cavity 2 , a molded part 3 is inserted, for example a molded part made of solid wood or plywood or a pressed wood part with a surface for kidney. The shape of the cavity 2 is chosen so that it is adapted to the shape of the molded part 3 . In the embodiment shown in Fig. 1, the inner wall 4 of the cavity 2 surrounds the surface 5 of the molded part 3 on all sides at an equally large, overall small distance, so that between the surface 5 on the one hand and the inner wall 4 on the other hand, the molded part 3 on all sides Gap space 6 is formed. The thickness of the gap can be between 0.1 mm and 1.5 mm, for example, depending on the desired thickness of the surface coating.

To hold the molded part 3 in this symmetrical position, in which the surface 5 is removed on all sides from the inner wall 4 , 1 holding pins 7 are arranged in the mold ( FIG. 2). These produce only very slight interruptions in the coating, which are readily acceptable, especially if they are arranged on the edges of the molded part, the surfaces of which do not appear on the outside.

The shape shown in FIGS. 1 and 2 is designed in two parts, so that the cavity 2 is accessible for inserting and removing the molded part 3 by separating the two parts. This two-part is shown in the drawing only very schematically, for example, the dividing lines can also run parallel to the central plane of the molded part 3 .

The cavity 2 is connected via a suction connection 8 to a suction source, not shown in the drawing, for example to a pump. The suction port 8 is preferably arranged at the lower end of the cavity 2 .

At the upper end, a filling connection 9 opens into the cavity 2 and is connected to a storage container in which the surface coating material used is kept in liquid form. It can be, for example, synthetic resins based on polyurethane, polyester-based or acrylic-based, which are preferably transparent.

To coat a molded part 3 , this is inserted into the cavity 2 , which is evacuated via the suction connection 8 after the mold 1 has been closed. The pressure in the cavity 2 is lowered.

Already during this suction or immediately thereafter, liquid surface coating material is filled into the cavity 2 via the filling connection 9 , preferably under elevated pressure, for example with the aid of a feed pump. This liquid surface material fills the gap space 6 completely and homogeneously.

As soon as the gap 6 is completely filled, the liquid surface coating material is cured, for example by heating the mold or by irradiation, preferably with UV radiation. For this purpose, molds are used whose material is transparent to the radiation used, for example molds made of glass, silicone or a transparent plastic. If other curing methods are used, the molds can also be made of steel, aluminum or non-transparent synthetic resins, for example.

After the surface coating material has hardened, the mold is opened, and the surface-coated molded part 3 can then be removed from the cavity. In many cases it turns out that a reworking of the surface is no longer necessary, with the appropriate properties of the inner wall 4 , the surface of the coated molding can be used directly for the end product.

The inner wall 4 can be completely smooth, so that a high-gloss surface is obtained, but structuring is also possible, so that, for example, a matt surface or a corrugated surface is formed.

In the embodiment shown in Fig. 1, the gap 6 surrounds the molded part 3 on all sides, so that an all-sided surface coating takes place.

In contrast, the molded part in the embodiment of FIG. 3 is inserted into the cavity 2 in such a way that it lies flat against the inner wall 4 on one side and a gap space 6 is formed only on the opposite side. Otherwise the structure is the same. When filling the cavity 2 with the liquid surface coating material, this passes through only on one side of the molded part on its surface, thus giving a one-sided surface coating. Otherwise the process is exactly the same.

It has surprisingly been found that the described methods compared to conventional methods of Application of material savings on the coating material from over 50% can be achieved. It is also possible to avoid polluting solvents, so this Process the big problems of solvent post-combustion and removal in the simplest way.

Claims (9)

1. A method for the surface coating of molded wood parts, characterized in that the wood molded part to be coated on the upper surface is placed in a cavity, the inner wall of which is a small distance from the wooden molded part in the area to be coated, and thereby between the inner wall and the surface Coating surface a gap extending over the entire surface to be coated with a substantially constant thickness, that the cavity is at least partially evauated, that during the evacuation or afterwards, a liquid surface coating material is filled into the cavity and that after complete filling of the gap, the liquid material hardens inside the cavity. 2. The method according to claim 1, characterized in that to un the liquid surface coating material fills the cavity with increased pressure.   3. The method according to claim 1 or 2, characterized net that the liquid surface material after the Filling the cavity through the translucent trained walls of the cavity with a för the hardening of the liquid surface material reducing radiation. 4. The method according to claim 3, characterized in that the radiation is an electromagnetic radiation in the UV range. 5. The method according to any one of the preceding claims characterized in that as a liquid surface surface coating material synthetic resins on polyurethane, Polyester or acrylic base used. 6. The method according to any one of the preceding claims, since characterized in that the coated wood takes molded part out of the cavity after curing and leaves without further surface treatment. 7. The method according to any one of the preceding claims characterized in that a cavity with a textured interior wall used.   8. The method according to any one of the preceding claims characterized in that the molded wood part in arranges the cavity that on all sides between the Surface of the molded wood part and the inner wall of the Cavity is a gap space is formed. 9. The method according to any one of claims 1 to 7, characterized characterized in that the wooden molded part flat directly on the inner wall of the cavity creates so that only in the other surface areas a gap between the surface to be coated che and the inner wall of the cavity is arranged.